How to fix AirPlay audio when you hear nothing at all.
1. Obviously, make sure the volume is turned up and not muted.
Places to check the volume:
-Volume control on the video window (example: youtube videos have a volume control near the lower-left when you mouse over them).
-Volume control on your device (F12 key on MacBook Airs).
-Volume control on the projector.
-If ceiling mounted, use the projector's remote. If the projector has external speakers plugged into it, also check that the speakers are turned on and adjust the volume on them.
-If wall mounted, use volume switch on the Extron wall switch.
2. Reboot the Apple TV.
-Call the tech support person in charge of your building and ask them to remotely restart your AppleTV. 90% of the time they can restart it remotely.
-Using an older Apple TV remote (white or all silver) hold down the menu and minus (down arrow) buttons until the light on the Apple TV flashes rapidly.
-Cycle the power to the Apple TV by unplugging its power cord for a few seconds and then plug it back in.
You may want to ask tech support or building services to do this for you if your Apple TV requires a ladder or step stool to reach.
The Apple TV is a small black box.
-If the projector is ceiling mounted, the Apple TV will likely be sitting on top of the projector.
-If the projector is wall mounted, the Apple TV will likely be hanging from a ceiling tile.
(If the projector is wall mounted, tech support might also need to cycle power to the Extron PoleVault switch box)